N-paraffins are raw materials for the production of biodegradable detergents, insecticides, and solvents, among other products, that are usually obtained from hydrocarbons that come from mineral sources such as petroleum.
Commercially, N-paraffins are produced by the process of adsorption in a trickle bed, after hydrotreatment, from the raw material kerosene.
Molecular screens are usually used as the adsorbent elements. These contain synthetic zeolite crystals in their structure, with limited and uniform sized pores, in such a way that only N-paraffins contained in a gaseous hydrocarbon mixture are adsorbed through these pores. Compounds called isomers (isoparaffins, naftenes and aromatics), which do not have a linear chain, pass through the existing empty spaces, and flow out through the top of the adsorber. However, a small fraction of these compounds are retained in the mesopores of the adsorbent material, which contaminates the product.
Consequently, after adsorption, the product containing the normal paraffins is hydrotreated, in order to determine its purity, and is fractioned right afterwards in N—C10/C13 and N—C14/C15 streams.
Due to the inherent costs of obtaining raw material hydrocarbon derived from petroleum, which is aggravated, in this case, by the need for paraffinic petroleum such as, the Brazilian petroleum baiano brand, which is becoming quite rare, and taking account, on a worldwide level, environmental questions which are being greatly affected by economic activities of modern civilization, the search for alternative sources has stimulated many researches. Renewable sources of energy have been of particular interest because in addition to contributing to the improvement of the environment, they are able to become an extra source of energy for some regions of the world.
In this context, agricultural inputs have been the object of rising interest, as far as its exploration being as a new way of utilization or being as insert them to other traditional inputs, make agricultural inputs economically attractive.
Important examples of this are vegetable oils, which are basically made up of fatty acid triglycerides, and are directly extracted from vegetable seeds, through pressing processes and/or extraction using organic solvents. In addition to their recognized applications in food industries, vegetable oils are also used in the cosmetic industry, and in the production of soaps, dyes, lubricants, and plastics among others.
Brazil, due to its great expanse of land, and its privileged geographical situation, agriculture is particularly relevant as a factor of great importance for regional socioeconomic development, through the exploration of extractivist agricultural landholding cultures for use in various productive sectors of the economy, including in the production of products that could be considered renewable sources of energy.
Thus, there is a great effort in Brazil to make the use of vegetable oils viable in the energy sector currently in practice, that in many cases besides it be economically more favorable, it produces a significant advantage for the environment through the creation of products that are less aggressive and less polluting to the environment.
For this, there is a need to develop new technologies that produce inputs and products that comply with environmental regulations which are more rigid.
Related Technique
Hydrotreatment is a catalytic process, in which hydrogen is used for the purpose of stabilizing various products compound of hydrocarbon and for eliminating undesirable compounds such as: sulfur, aromatics, nitrogen, and olefins.
As known in the state of the art, the principal reactions that occur in the reactor during the hydrogenation process are:                a. Saturation of olefins—elimination of unsaturated chains.Ex: H2C═CH—CH3+H2→H3C—CH2—CH3 (propene→propane)        b. Saturation of aromatics—transformation of the aromatics in naphthenes and then transforming these in saturated compounds.Ex: Benzene→Cyclohexane        c. Hydrodesulfurization (HDS)—elimination of sulfur                    MERCAPTANS (R—SH):H3C—CH2—CH2—SH+H2→H3C—CH2—CH3+H2S            SULFIDES (R—S—R)H3C—CH2—CH2—CH2—S—CH2—CH2—CH3+2H2→H3C—CH2—CH2—CH3+H3C—CH2—CH3+H2Swhere the removal of the compounds above mentioned increase the concentration of butanes and propanes in the stream.                        THIOPHENES—their hydrogenation increase the concentration of butanes.        DISULFIDES (R—S—S—R)—the removal of these compounds increase the concentration of methane and hydrogen sulfide.H3C—S—S—CH3+3H2→2CH4+2H2S.        d. Hydrodenitrogenation (HDN) elimination of nitrogen and after this reaction, an increase in the concentration of pentane and ammonia occurs.CH3—CH2—CH2—CH2—CH2—NH2+H2→H3C—CH2—CH2—CH2—CH3+NH3         e. Deoxygenation→elimination of oxygen        f. Hydrocracking→when occurs a large molecules cracking producing light gas.C10H22+H2C9H2O+CH4.        
In the case of the production of N-paraffins, the hydrotreatment stage follows the initial stage of adsorption, aiming purifying the N-paraffins stream thus obtained.
At this point of the usual process, this invention adds a percentage of vegetable hydrocarbon oil into the industrial process stream, producing a mixture with the mineral hydrocarbon oil, which will be hydrotreated to obtain the N-paraffin product, which will be explained in more detail further.
According to production and/or operational needs, the vegetable hydrocarbon oil may also be submitted to hydrotreatment (HDT), in its pure state, on the condition that it be properly chosen according to the length of its chain, which preferably must present the highest possible content in the range of C12-C14 in order to be more compatible to be submited to the process.
Thus, the HDT of pure vegetable hydrocarbon oils, or in a mixture of any proportion with mineral hydrocarbon oils, will produce N-paraffins C10-C13 suitable for use as inputs, such as, raw material for the production of detergents, since the load of vegetable hydrocarbon oil to be introduced into the treatment process be properly selected for production of N-paraffins within the range of interest of C10-C13, and following using the already known hydrorefining technology, and by the use of commercial catalysts available.
The literature of patent presents some documents in the hydrogenation of vegetable oil medium, but these documents do not consider in their scope the intended range covered by this invention.
For example, the hydrogenation of vegetable oils combined with mineral oil is known by the U.S. Pat. No. 2,163,563, which processes vegetable oils mixed in a stream of mineral oil in the presence of hydrogen at high pressure [5 MPa to 50.6 MPa (50 to 500 atmospheres)], using a reduced Ni catalyst supported in alumina. The converted vegetable oil is separated by distillation and the mineral oil is recycled. However, this patent does not involve hydrotreatment of a combined load of petroleum and vegetable oils through an HDT process.
U.S. Pat. No. 4,300,009 describes a catalytic conversion of anabolites (substances formed in the anabolic process) as resins, vegetable oils and fats in liquid hydrocarbons, in the presence of zeolites with an effective pore size bigger than 5 Angstrom. The products generated have the boiling point at the range of gasoline's boiling point.
U.S. Pat. No. 5,233,109 describe a synthetic crude oil produced by catalytic cracking of a biomass material such as, a vegetable or animal oil in the presence of a catalyst that is alumina with or without silica and/or a zeolite component and/or rare earths and/or sodium oxide. The reaction is carried out in the presence of a carrier gas that may be air, nitrogen, argon, hydrogen and a hydrocarbon obtained in petroleum refining.
U.S. Pat. No. 5,705,722 describes a process to produce additives for diesel fuel with an elevated number of cetane and it functions as an agent to improve ignition of the fuel. In the process, the biomass, containing a high proportion of unsaturated fatty acids, wood oils, animal fats and other mixtures, is submitted to hydroprocessing, placing the load in contact with gaseous hydrogen in the presence of a hydroprocessing catalyst under hydroprocessing conditions in order to obtain a mixture of product. This mixture is then separated and fractioned to obtain a hydrocarbon product with boiling point at the range of diesel's boiling point, being this product the additive with a high cetane number. It is not mentioned within this document concerning the addition of a petroleum hydrocarbon to the biomass load which is being hydroprocessed.
U.S. Pat. No. 4,992,605 uses hydrorefining with sulfided catalyst (NiMo and CoMo) in the presence of hydrogen (pressure of 4 to 15 MPa) and temperature in the range of 350° C. to 450° C.
This patent describes the processing of pure vegetable oils such as canola, sunflower, soy, palm and wood oil that is a waste product from the wood pulp industry. The final objective is to obtain a stream with a high cetane number to be added to the diesel in the refinery; however, specifications at low temperatures are damaged. This patent does not consider a mixture of a hydrocarbon with vegetable oil in the hydrorefining.
U.S. Pat. No. 5,972,057 describes the transesterification of vegetable oils, mainly spent oils used in frying, with methanol and ethanol, in order to produce a fuel similar to mineral diesel fuel, however the process involves the consumption of an expensive reagent (alcohol) but its by-products (glycerin, etc.) must be separated to avoid damages to the motor.
Therefore, in spite of developments in the technology, there is still a need for a technic to process hydroconversion of vegetable oils which seeks to obtain N-paraffins.